Gallon Environment Letter – the daily edition – a policy letter from the Canadian Institute for Business and the Environment

GE Hybrid water heater a great idea but with perhaps one limitation

General Electric Company has introduced what it calls a “hybrid” domestic water heater. The water heater, which is designed to have the same footprint as, and be completely interchangeable with, a standard domestic electric water heater uses a heat pump to extract heat from the surrounding air. This heat is used to heat the water. Supplementary 2500 watt conventional heating elements also provide heat for the water when the heat pump cannot keep up with hot water usage. GE claims that the hybrid water heater, branded as GeoSpring, is up to 62% more efficient than a conventional water heater.

The heat pump part of the GeoSpring is designed to work only in an ambient temperature range of 45F to 120F. The challenge is that, if located in a heated space, the hybrid water heater will remove heat from heated air and cause the furnace to work longer to replace the heat transferred to the water. If located in an air conditioned space, the hybrid heater will actually assist the air conditioning and reduce the energy usage of the air conditioning unit.

GE states that, typically, water heaters are located in what it calls “unconditioned spaces” such as garages, basements, and attics. That may be the case in the US but is almost certainly not the case in most Canadian homes where lack of heating would cause water pipes to burst in winter freezing. So, in Canada, a heat pump water heater will simply be taking heat out of the warmed air and causing the heating system to work harder, a process that will also contain some inefficiencies and which will likely end up using more energy in winter months than the hybrid water heater saves.

GE tries to address this by stating that if the heating season (furnace) and cooling season (air conditioner) are of roughly equal lengths, then the extra space heating required will be offset by the cooling energy saved and the energy savings of the hybrid water heater will still be realized. However, no data are presented to substantiate this, the statement fails to take into account the inefficiency of heating a space to provide heat to a heat pump which then heats water, and in much of Canada the cooling season is much shorter than the heating season.

GallonDaily commends GE for introducing a piece of technology that has the potential to significantly reduce energy consumption in many homes. It is the kind of technology leap that we need to address climate change and energy supply challenges. However, for it to be convincing, the Company also needs to provide information on how the water heater performs in a range of heated home situations that correspond to typical Canadian homes. Otherwise many purchasers may end up being seriously disappointed and may even initiate claims of misleading advertising.

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2 responses

I haven’t used one yet but my electric-resistance water heater just died. I understand your reservations (noise is also cited as an annoyance) but consider this. My wood-heated home has a very warm basement for 6 months of the year. Any “scavenged” energy harvested by the heat-pump will be, effectively “renewable” and without any direct connection between the 2 devices. (People who put coils and other connections between their wood-burning device and their water-heater give me, and the insurance industry, the willies….) That sounds like a no-brainer to me, considering electricity here in rural Ontario works out to between 14 and 20 cents per KWH. (the less you use, the more it costs….) These things promise a saving of up to 3000 KWH per year. However, if your situation permits and you act now…..it’s a DEHUMIDIFIER!! My hydro bill goes up in the summer as I try to keep my house healthy by dehumidifying basements and crawl-spaces that are built on bedrock and can never be perfectly moisture-proofed. This is a significant additional benefit. A dehumidifier is a pig for energy and acts like a fridge that never turns off. Given the potential, at least within a niche of several ten-thousands of homes, this technology should be more widely deployed.
Your old friend, Bill Armstrong. Cormac, Ontario.

Your site is new to me today and your critical eye is much appreciated by a well-intentioned but ill-informed consumer. Your logic is reasonable to me, and certainly some hard evidence in our Canadian climate about the increased heating expense vs the hot water energy savings is required.
I wonder though:
– if my tank is in a basement area not “lived in” and the thermostat for the house is up one floor and through two closed doors, is the ambient heat theft that great?
– Would it not potentially reduce the heat in the basement area where the tank is located without significantly increasing the demand on the furnace?
– Would the temperature at which the hot water heater is set have a significant impact?
Delighted to have discovered your insights. Carla Berend

A comment too for Mr Armstrong regarding dehumidifiers: a well respected architect / engineer (I have heard him referred to as the nemesis of real estate agents who would prefer to a stamp of approval vs a sound and complete home inspection) explained the following when we called him in for our annual spring thaw floods:
as the foundation is made of cement it will always be humid; to attempt to dehumidify your basement is literally to suck moisture from the ground surrounding the structure inside; it will never be dry.
His solution to the rivulets that appeared each spring (never in the same place)was to lay a moisture-proof membrane overlapping which started two feet up the wall against 1×2 “mini studs” that allowed air and water to circulate. Carpeting was laid over the membrane, and drywall in the “lived in” portions.
The basement felt drier than it ever had – a comfortable living environment – and we lived happily with the overflows from torrential rainstorms and sudden snow thaws in spring because we never knew when and where water was seeping through!
It was truly a simple, but elegant solution to the earlier mustiness and water damage we had tolerated with discouragement. My neighbour who spent $$$ digging up the earth around the foundation, caulking any cracks and re-doing the drainage system around the whole house was never satisfied with the costly, and falsely proferred “solution”. Hope this helps you.